Korean Agriculture Research Articles

Sustainable animal agriculture in the United States and the implication in Republic of Korea.

Agriculture has played a significant role in the national economy, contributing to food security, driving economic growth, and safeguarding the dietary habits of the population. Korean agriculture has been compelled to focus on intensive farming due to its limited cultivation area, excessive input costs, and the limitations of agricultural mechanization. In the Republic of Korea (R.O.K), the concept of environmentally friendly animal agriculture began to be introduced in the early 2000s. This concept ultimately aims to cultivate sustainable animal agriculture (SAA) through environmentally friendly production practices, ensuring the healthy rearing of animals to supply safe animal products. Despite the government's efforts, there are still significant challenges in implementing environmentally friendly agriculture and SAA in the R.O.K. Therefore, the objective of this review is to establish the direction that the animal agriculture sector should take in the era of climate crisis, and to develop effective strategies for SAA tailored to the current situation in the R.O.K by examining the trends in SAA in the U.S. The animal agriculture sector in the U.S. has been working towards creating a SAA system where humans, animals, and the environment can coexist through government initiatives, industry research, technological support, and individual efforts. Efforts have been made to reduce emissions like carbon, and improve factors affecting the environment such as the carbon footprint, odor, and greenhouse gases associated with animal agriculture processes for animals such as cattle and pigs. The transition of the U.S. towards SAA appears to be driven by both external goals related to addressing climate change and the primary objectives of responding to the demand for safe animal products, expanding consumption, and securing competitiveness in overseas export markets. The demand for animal welfare, organic animal products, and processed goods has been increasing in the U.S. consumer market. A major factor in the transformation of the U.S. animal agriculture sector in terms of livestock specifications is attributed to environmentally friendly practices such as high-quality feed, heat stress reduction, improvements in reproductive ability and growth period reduction, and efforts in animal genetic enhancement.

A Study on Rice Growth Monitoring Using Drone Remote Sensing

Rice paddy is one of the key crops of Korean agriculture and it has long been regarded as an important crop. Due to the high self-sufficiency of rice in Korea, the need to establish systematic rice paddy field data is increasing, and rice paddy research using remote sensing is being conducted several times in Korea. The optical satellite remote sensing method faces difficulties in data acquisition due to the abundance of clouds caused by the summer monsoon season, a characteristic of the domestic climate. However, the drone remote sensing method equipped with an optical sensor has the advantage of being able to freely acquire data, avoiding periods with high cloud cover. In this study, a drone equipped with a multispectral optical sensor was utilized to measure the height of rice paddy. Compared to satellites, drones provide the advantage of flexible timing for observations, allowing for the acquisition of high-frequency time-series data according to specific preferences. In this study, we seek to obtain values related to rice growth rates by analyzing optical data acquired through drone remote sensing. The DJI MAVIC 2 PRO drone was employed, and the Metashape program was utilized to generate a highresolution digital elevation model (DEM) from optical data. After the harvest period, rice-free rice paddy data were assumed to be digital terrain model (DTM), the height of the rice paddies. During the rice growth period, a digital surface model (DSM) was generated from drone imagery, and by calculating the difference between DSM and DTM, the height and growth of the rice plants were observed. Using network GPS measurement data, we validated monthly DEM models. This allowed us to anticipate the acquisition of precise rice growth data throughout the year, from planting to harvest.

Estimation of Air Pollutant Emissions by Tractor Utilization in Korea

The utilization of tractors is essential because of both the shortage of agricultural labor forces and the rapid aging of farmers in Korean agriculture. Tractors can be classified into two types: a walking tractor called as a power tiller, and a riding tractor. In this study, diesel emission inventories of tractors were established and variations of air pollutants were analyzed with each other using 2011 and 2019 survey data in Korea. Agricultural tractors including walking and riding types, which were categorized into three levels via the rated output power, were the main sources of diesel emissions. The emission inventory including CO, NOx, SOx, TSP(PM10), PM2.5, VOCs, and NH3 were established using a Tier 3 methodology. The total amount of emissions using agricultural tractors was decreased by about 13% from 2011 to 2019. The number of walking tractors were decreased by about 19% in 8 years; on the other hand, that of riding tractors were increased by about 12%. However, the emission reduction is about 48% for walking tractors, and the emission increment is about 5% for riding tractors. Thus, the total emission from agricultural tractors was decreased by about 16% in those periods. It is due to the decrease of 21% and 15% in the hours of use of walking and riding tractors, respectively, in 2019. Walking tractors mainly emit air pollutants from spraying and transporting. Riding tractors emit about 61% of the total air pollutants mainly from soil preparation and transporting operations. The geographic information system (GIS) was used to visualize the distribution of air pollutants in Korea. High-emission generating regions and the changes of emissions over 8 years were clearly seen in the GIS analysis. High air-pollutant emitting regions are mainly located in the western and southern regions of Korea, which have plenty of arable areas compared to other regions in Korea.

First Report of Sharp Eyespot of Oat (Avena sativa) Caused by Ceratobasidium cereale in Korea.

Along with barley and wheat, oats (Avena sativa) are cultivated as winter crops in Korea, and the total area for oat cultivation is 103 ha in 2021. From late March to early April 2021, sharp eyespot symptoms on oat (cv. Choyang) leaf sheaths and straws were observed in two commercial fields located in Haenam (N34°38'35.04588/E126°38'31.00668) and Gangjin (N34°38'9.46788/E126°37'19.44984), Jeollanam-do, Korea. The incidence was 5% and 7%, respectively. Small brown spots were irregular circles that began to appear on the lower sheaths, and the spots gradually enlarged in the upper part of the sheaths. The center of each lesion turned whitish-brown with dark brown margins, resulting in a blight of the sheaths. Three plants displaying typical sharp eyespot lesions were collected from each of two individual regions, Haenam and Gangjin. To isolate the causal pathogen, two infected tissues (5  5 mm) from the collected plants were surface-sterilized by treating them with 70% ethanol for 1 min and 1% NaClO for 1 min immediately after being treated with 95% ethanol for 1 min. Subsequently, the samples were rinsed three times with distilled water, dried with sterile filter paper, transferred to 1.5% water agar supplemented with 100 ppm streptomycin, and then incubated in the dark at 25°C. Hyphae emerging from the randomly selected three independent tissues from each location were subcultured on potato dextrose agar (PDA, Sparks, MD 21152, USA), resulting in three independent isolates (HNO-1, HNO-2, HNO-3) from Haenam and three (KJO1-1, KJO1-2, KJO1-3) from Ganjin after single-hypha-tip purification. Colonies on the PDA were pigmented white at first and subsequently changed to light brown after 2 weeks. All collected isolates formed globose and irregular dark brown to black sclerotia on PDA after 2 weeks. Binuclear hyphae were white to dark brown in color, branched at right angles with a septum near the branch, and multinucleate cells, suggesting that these isolates belonged to Ceratobasidium cereale (Boerema et al., 1977; Burpee, 1980; Sharon et al.,2008). For molecular identification, the ITS (GenBank accession nos. MW691851-53 for HNO-1 to HNO-3; MW691857-59 for KJO1-1 to KJO1-3), LSU (OQ397530-35), rpb2 (OQ409878-83), tef1 (OQ409884-89), and atp6 (OQ409890-95) regions of six isolates were amplified using the primer pairs ITS4/5 (White et al., 1990), LROR/LR5 (Vilgalys and Hester, 1990), bRPB2-6F/bRPB2-7.1R (Matheny, 2005; Reeb et al., 2004), TEF1-F/TEF1-R (Litvintseva et al., 2006), and ATP61/ATP62 (Kretzer and Bruns, 1999), respectively. The sequences of ITS region showed 99.7% identity with C. cereale strain WK137-56 (KY379365) and 99.8% with Ceratobasidium sp. AG-D (KP171639). Using the MEGA X program (Kumar et al. 2018), a maximum likelihood phylogenetic analysis based on the concatenated ITS-LSU, rpb2, tef1 and atp6 sequences placed the six isolates within a clade comprising C. cereale (Gónzalez et al.,2016; Ji et al., 2017; Tomioka et al., 2021; Li et al., 2014). Two representative isolate, HNO-1 and KJO1-1, were deposited in the Korean Agriculture Culture Collection (Accession No. KACC 49887 and 410268, respectively). For pathogenicity, the six isolates were cultured on sterilized ray grains at 25°C in the dark for 3 weeks as the inoculum. Five oat (cv. Choyang) seeds were sown per pot containing 80 g of the infected ray grains mixed with 150 g of composite soil and 150 ml of water (Baroker Garden Soil, Seoul Bio Co., LTD). The control was treated with 80 g of the sterilized ray grains mixed with 150 g of composite soil and 150 ml of water. All inoculated and control pots were placed in a 20°C growth chamber with a 12-h photoperiod and 65% humidity. Typical sharp eyespot symptoms were observed on the oat sheath of seedlings three weeks post-inoculation. No symptoms were observed in the control seedlings. The infection assays were repeated thrice, with similar results. The pathogen was successfully re-isolated, and its identity was confirmed via morphological and molecular analyses. In Korea, few etiological studies have been conducted on oats because they are less economical than barley and wheat. Sharp eyespot disease caused by C. cereale has already been reported in barley and wheat (Kim et al., 1991); however, this is the first report of this disease in oats in Korea.

First Report of Brown Spot Caused by Alternaria alternata on Potato (Solanum tuberosom L.) in Korea.

In June 2020, brown spot symptoms were observed in a commercial potato field located in Yeocheon, Gyeonggi Province, Korea. The symptoms were similar to those associated with early blight. Brown lesions on leaves were circular and expanded rapidly under high humidity and warm temperatures ranging 12°C at night to 30°C during daytime. Over 60% of potato (Solanum tuberosum L. cv. Superior) leaves showed the symptoms. For fungal isolation, infected leaf tissues (5 × 5 mm) from 14 infected samples were immersed in 70% ethanol for 1 min, rinsed three times in sterilized water, dried, placed on water agar amended with 100 ppm of streptomycin, and then incubated in the dark at 25°C. Hyphae emerging from the tissues were subcultured on V8-Juice agar (8% of V8-Juice, 1.5% agar, pH 7), and the obtaining cultures were subjected to single-spore isolation, resulting in 14 isolates (SYP-934~947). Three representative isolates, SYP-934 to SYP-936, were deposited in the Korean Agriculture Culture Collection (Accession Nos. KACC 410058 to KACC 410060). Conidia (n = 100) produced on the colony were brown, ellipsoid to ovoid with walls ornamented, 1 to 6 transverse and 0-3 vertical septa, and length × width of 20-45 × 7 to 24 μm (n = 100). Their morphological characteristics were consistent with Alternaria alternata (Simmons, 2007; van der Waals et al., 2011; Woundenberg et al. 2015). Sequences of the following loci in the 14 isolates were determined as described in Woundenberg et al. (2013 and 2014: the internal transcribed spacer (primer pairs VG9/ITS4, GenBank accession nos. OP581413-25), glyceraldehyde-3-phosphate dehydrogenase (gpd1/gpd2, OP588286-99), RNA polymerase second largest subunit (RPB2-5F2/fRPB2-7cR, OP588314-27), translation elongation factor 1-alpha (EF1-728F/EF1-986R, OP588300-13), Alternaria major allergen gene (Alt-For/Alt-Rev, OP588328-41), endopolygalacturonase (PG3/PG2b, OP588342-55), and an unknown gene region (OPA10-2R/OPA10-2L, OP588356-68). A neighbor-joining phylogenetic analysis based on the concatenated gene sequences, which was performed using the MEGA X program (Kumar et al., 2018), placed the 14 isolates in the clade containing A. alternata isolates. To test pathogenicity, one-month-old potato (S. tuberosum cv. Superior) plants grown in a 25°C growth chamber were sprayed with conidial suspensions (1×106 conidia/mL) prepared from 14-day-old cultures of three isolates (KACC 410058 to KACC 410060). Sterile distilled water was used as the control treatment. The inoculated pots were placed in a plastic box to maintain high humidity and incubated in the dark at 25°C for 2 days. The plants were transferred to a growth chamber (16h light with over 70% humidity at 25°C). Symptoms were first observed after 3 days post inoculation (dpi) with all three isolates, and severe brown spot symptoms were observed after 7 dpi. No symptom was observed in the control treatment. The pathogenicity assay was repeated at triplicate. Reisolated cultures from lesions were confirmed to be A. alternata based on their sequence at the rpb2 locus, thus fulfilling Koch's postulates. Alternaria alternata has been reported to cause brown spot and leaf blight on potato leaves in Israel (Dorby et al., 1984) and South Africa (van der Waals., et al. 2011). To our knowledge, this study is the first report of A. alternata causing brown spot disease in Korea.

국내 꿀벌에서 Lotmaria passim 검출

Apis mellifera, also known as the western honey bee, is one of the most important pollinators of flowering plants, including many agricultural crops. In Korea, the number of honey bee pollinations have been fluctuating in recent years. Several honey bee parasites have been presumed as probable causes of decline. Lotmaria passim is the most virulent trypanosome parasite which usually infects the A. mellifera intestine. After first report in 1911, L. passim widely present in South America and Europe including Uruguay, Argentina, Chile and Spain. However, the presence of this virulent trypanosome is not reported in Korea before. The aim of the present work was to provide the evidence of detection of the L. passim from A. mellifera in Korean agriculture. A. mellifera from three sites; Gwangju, Yangpyung and Toechon was ground with liquid nitrogen and mRNA was extracted. Quantitative real-time PCR (qPCR) was used to investigate the presence of L. passim nucleic acid. The amplification products were also sequenced and analyzed. L. passim was detected from honey bee in Yangpyung. PCR products were sequenced and the nucleotide sequence was aligned to the complete L. passim sequence from NCBI database, and the sequence were revealed 100% identity. The honey bee parasitic trypanosome L. passim was found in the Korea honey bee first time and should be considered as a potential contributor of honey bee infectious disease in Korea.

Developing an Agent-Based Model to Mitigate Famine Risk in North Korea: Insights from the “Artificial North Korean Collective Farm” Model

North Korea experienced a catastrophic famine in the mid-1990s that resulted in millions of deaths. This study aims to build an agent-based model to understand the risk of land degradation and famine in North Korea and explore potential solutions to mitigate this risk. The model concept reflects the general information of collective farms in North Korea, which was set in 1960, and the abstract of the social–ecological system of North Korean agriculture. The model comprises the agent, environment, and external factors. An agent is defined as a household that decides its labor allocation and land use by how much food it has. The environment is set to multiple layers that represent the soil environment of the farm, affected by agents’ decisions. The external factors reflect a land-use restriction policy, international trade (food aid), and climate change. We calibrated the model using data from North Korea and simulated various scenarios. Our findings suggest that the famine in the model would occur around 35 years later, almost reflecting the 1995 famine in the real world. The scenario-based simulations show that additional food aid or import could delay the famine, but fundamental solutions are needed to break the vicious circle of land degradation and declining food yield. Our study provides insights into the complex adaptive system of North Korean agriculture and the critical points of famine risk. Our agent-based model can be a useful tool for policymakers and researchers to explore potential solutions and inform risk management strategies.

Role of Smart Farm as a Tool for Sustainable Economic Growth of Korean Agriculture: Using Input–Output Analysis

This study focused on smart farms in Korea to confirm that the fourth industrial revolution technology is a tool that can be used for sustainable economic development in agriculture. This study used the input–output table, which included the production-inducing effects of the demand inducement model, value-added inducing effects, supply shortage effects of the supply inducement model, and the interlinkage effect. These methods were used to compare the impact of smart farm machinery on agriculture and the impact of smart farms on the Korean economy compared to conventional agriculture, thereby confirming the extent of the effect of fourth industrial revolution technology on agriculture. This study was conducted to determine whether this agricultural sector could lead to sustainable economic development. The analysis revealed that the production-inducing effects of smart farms showed a greater ripple effect than those of the agricultural sector. However, both value-added inducing effects and supply shortage effects showed a larger ripple effect in the agricultural sector. Considering only the indirect effect, the smart farms were found to evenly affect secondary and tertiary industries. In the case of value-added inducing and supply shortage effects, agriculture was found to have a greater impact on the secondary industry, whereas smart agri-machines and farms had a greater impact on the tertiary industry. Moreover, according to the interlinkage effect, agriculture was classified as a raw industry with final demand, and smart farms as a manufacturing industry with intermediate demand. These results have several implications. For the fourth industrial revolution technology to lead sustainable economic growth in agriculture, continuous creation of new value by developing various types of business models linked to other industries in consideration of the industrial characteristics of smart farms and agri-machines is necessary. In addition, to fully demonstrate the economic effects of smart farms, continuous management and support are required so that smart technologies can be strategically utilized in the agricultural sector.

Changes in Microbial Community Structure in Response to Gummosis in Peach Tree Bark.

Peach gummosis disease has been identified as a serious challenge in Korean agriculture and has developed to become a major cause of agricultural productivity losses. However, treatments for gummosis have not been systemically established and studies of the microbiome closely related to this plant disease are lacking. Therefore, we analyzed the bacterial and fungal communities in the bark and rhizosphere soil of healthy peach trees and those with gummosis. Through high-throughput sequencing, we obtained unprecedented insights into the bacterial and fungal dynamics of each group, including their diversity and taxonomic classification, as well as network analyses. We found that the presence of gummosis drives a significantly higher alpha diversity in the bark bacterial community. Peach gummosis bark mycobiomes included greater numbers of opportunistic pathogens such as Ascochyta, Botryosphaeria, Saccharomyces, Nectriaceae_NA, Trametes, and Valsaceae_NA. However, the microbiome also included bacteria beneficial to plant growth and the production of polysaccharides-namely, 1174-901-12, Catenibacterium, Cutibacterium, Friedmanniella, Methylobacterium-Methylorubrum, Pseudomonas, Rhodobacter, and Sphingomonas. Furthermore, we confirmed that gummosis induced a more complex structure in the bark microbiome network. We conclude that the findings of this study provide a valuable aid in profiling the overall peach tree microbial ecosystem, which can be utilized to develop precise biomarkers for the early diagnosis of gummosis.

A Study on the Impact of RCEP Tariff Reduction on Korea’s Agricultural Trade: Simulation Analysis Based on the GTAP Model

Purpose The purpose of this paper is to analyze the impact of RCEP tariff reduction on South Korea’s agricultural trade, so as to help the government and agricultural personnel make relevant preparations in advance. Design/Methodology/Approach Based on agricultural trade data between South Korea and RCEP countries, firstly, through the analysis of the RRCA and TCI index, the basic situation of trade competitiveness and complementarity of agricultural products between South Korea and RCEP member countries is clarified. Then, with the help of the global trade analysis model (GTAP model), this paper makes a progressive study on the impact of the RCEP on South Korea’s agricultural trade from the perspective of tariff reduction. The impacts of the four cases are predicted in chronological order. Findings Excluding the influence of other bilateral FTAs, this paper makes an accurate estimation of the impact of RCEP tariff reduction on Korean agriculture. Research shows that although it has a negative impact on most agricultural products, in the long run, participating in the RCEP is more beneficial than resisting. Research Implications In the management of this paper, this study makes a quantitative analysis of the impact of the RCEP in the future, which is helpful to objectively look at the economic impact of regional economic integration. It is conducive to correctly understand the adverse impact of the RCEP on Korean agricultural products, and does not exaggerate this impact, which will also provide reference for other scholarly follow-up research.

영농형 태양광 설치에 따른 농가소득 영향분석

This study examined the impact of photovoltaic use on farm household income. Construction of photovoltaics on agricultural areas of crop planting could be a benefit to farmers depending on the incentives. We designed a farm household income calculation model to considering farm income, off-farm income, transfer income, and non-current income. Reduced production by photovoltaics causes a decrease in farm income, while power generation increases the off-farm income. Our model generated income changes based on assumptions of financial and electrical supports that affect off-farm income and productivity that influence farm income. Our results showed that farm household income could be increased if benefit supports followed the current condition. The farm income slightly decreased, but the off-farm income showed a large relative increase, producing an overall increase in income. However, if benefit supports were worse than our baseline assumptions, the farm household income could be decreased. Therefore, our study implies the effect of benefit supports for photovoltaics in Korean agriculture on farm household income. These results can help policy makers and farmers determine the use of photovoltaics in agriculture.

Comparative Analysis of Korean Agriculture and Forestry ODA Projects and Policy Directions

Comparative Analysis of Korean Agriculture and Forestry ODA Projects and Policy Directions

5·16 군사정권기 ‘중농 정책’ 다시 보기 - 농어촌 고리채 정리법과 농산물 가격유지법을 중심으로

This thesis deals with the agricultural policy of the 5·16 military government, which advocated the agricultural first policy. The “military government” implemented Anti Usury Act and Agricultural Product Price Maintenance Act. Those policies has already discussed since the 1950s. In the actual implementation process, each policy produced side effects. Financial crisis in rural areas exacerbated and farmers’ losses were not conserved. On the other hand, the government did not come up with an active alternative to the food supply and demand problem that would come along with the decrease in rice harvest. In result the food crisis intensified in 1963. Agricultural policy of the 5·16 military government was not a policy planned in the long-term view to reform and improve the structure of Korean agriculture or the overall food supply and demand system. But rather a measure to address the immediate problems. Therefore, it was not possible to improve farm household income or change the structure itself to sacrifice agriculture just by touching the usury and price maintenance. This is the fundamental limitation of the military regime’s “Agricultural First Policy”.

Phanuromyia ricaniae Nam, Lee Talamas sp. n. (Hymenoptera: Scelionidae) reared from the eggs of Ricania shantungensis Chou Lu (Hemiptera: Ricaniidae) in Asia.

The genus Phanuromyia in the subfamily Telenominae (Hymenoptera: Scelionidae) consists of 60 described species, for which host records indicate they are egg parasitoids of lanternflies and planthoppers (Hemiptera: Auchenorrhyncha). In this study, we describe a new species of the genus, P. ricaniae sp. n., reared from the eggs of a planthopper, Ricania shantungensis Chou Lu (Hemiptera: Ricaniidae). This planthopper has been considered as a serious invasive pest in South Korean agriculture. Ricania shantungensis has a wide host range, including economically important crops such as apple, peach, and pear. Phanuromyia ricaniae therefore has the potential to be a biological control agent against ricaniid planthoppers.

Assessing Economic Value of Social-cultural Function of Korean Agriculture

Assessing Economic Value of Social-cultural Function of Korean Agriculture

생산계획과 생산자의 게임스맨십 : 한국농업의 사례를 중심으로

생산계획과 생산자의 게임스맨십 : 한국농업의 사례를 중심으로

1970년대 박정희 정권의 원료농산물 증산정책과 가공기업의 활동 - 주정기업의 고구마 수급을 중심으로 -

In the 1970s, the Park Chung-Hee regime promoted to increase the production of raw agricultural product. In order to motivating farmers to take part in it, the government had to secure enough demand. It was a matter of creating a balanced in supply and demand.BR In the case of raw sweet potato, the government had passed the responsibility for taking over the sweet potatoes to the sprit(酒精) companies. Therefore the production of sweet potato increased in the mid-1970s. However, as it depended on the companies’ interest, the balance in supply and demand was fragile. Finally, a few spirit companies avoided purchasing sweet potatoes just for their own profit, and the damage was to be taken by farmers.BR The increase in raw agricultural products laid on the process of capitalist reorganization of Korean agriculture. In the process, production increased, but demand was not guaranteed. As a result of the irresponsible agricultural product increase policy, the imbalance in supply and demand was structured in agriculture.

Constructing County-Level Data for Agricultural Inputs and Analyzing Agricultural Productivity, 1951-1980

Constructing County-Level Data for Agricultural Inputs and Analyzing Agricultural Productivity, 1951-1980

Flower Habitat Supplementation can Conserve Pollinators and Natural Enemies in Agricultural Ecosystem : Case Study in the Pepper Field

Pollinators play important roles for crop production as well as maintenance of wild plants’ reproduction. Pollinator dependency in Korean agriculture have increased, but the degradation of habitat quality pose significant threats to pollination in agroecosystem. Provisioning flower habitat is one of the major activities to increase pollinator abundance and richness. We tested the effect of flower habitat supplementation on the pollinator, pest and natural enemy abundance in pepper field. Results showed that Hymenopteran pollinators were more abundant in the pepper plots close to the flower habitat. Among natural enemies, the similar pattern from pollinators was observed to parasitoids in the family of Eulophidae, but not to those of Ichneumonidae. There were no statistically significant differences of insect pests like aphids and thrips, as well as pepper production among plots in the pepper field. Even limited spatial scale, this study showed supplementing the flowering plant habitat to the agricultural landscape could conserve and boost pollinators and natural enemies, and possibly resulting better fruit production by pollination service.

Evaluation of phenolic compounds from viroid-free and viroid-infected apples using HPLC-PDA-ESI-MS/MS.

Apples are the most consumed fruits in Korea and have played an economically important role in Korean agriculture. However, widespread viroid infection in apples had been reported in recent years. The objective of this study was to clarify the relationships between viroid-disease resistance and phenols content of three apple cultivars: "Fuji", "Gamhong", and "Hongro". A model for distinguishing between viroid-free and viroid-infected apples was also developed. Phenolic compounds in samples were detected using high-performance liquid chromatography photodiode array tandem mass spectrometry (HPLC-PDA-MS/MS) and quantified using an ultraviolet detector at 280nm. A C18 -column and 0.5% aqueous acetic acid-methanol were used as the stationary and mobile phase. The HPLC method was validated with respect to linearity, precision, accuracy, and recovery. Multivariate analysis was performed using phenols content as variables to classify viroid-free and viroid-infected apples. An accurate method for identifying and quantifying phenol compounds in apple samples was developed and validated. In response to viroid infection, considerable increases in the content of dihydrochalcones (in all three cultivars), hydroxycinnamic acid (in "Fuji"), and flavonols (in "Hongro") were observed. The flavonols content in "Fuji" viroid-infected samples, however, decreased dramatically. An effective linear discriminant model, with 98.2% accuracy and 94.6% predictive ability, was achieved to discriminate between viroid-free and viroid-infected samples. The developed HPLC method is suitable to identify and quantify phenol compounds in viroid-free and viroid-infected apples. A hypothesis about the significance of these compounds in viroid-disease resistance was proposed. The linear discriminant model with high predictive ability is useful for identifying viroid-infected apples in the orchards.